Systems and methods to transmit information among a plurality of physical upstream channels

ABSTRACT

A communication system includes a supervisory node (e.g., a headend) and one or more remote nodes (e.g., cable modems). The supervisory node or a remote node monitors a characteristic associated with the communication system. Remote node transmits an upstream communication among a plurality of physical upstream channels based on the characteristic. The average transmit power used to transmit the upstream communication among the plurality of physical upstream channels is no greater than the average transmit power that would be necessary to transmit the upstream communication using a single physical upstream channel at a lower data rate.

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS Continuationpriority claim, 35 U.S.C. §120

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. §120, as a continuation, to the following U.S. Utility PatentApplication which is hereby incorporated herein by reference in itsentirety and made part of the present U.S. Utility Patent Applicationfor all purposes:

1. U.S. Utility patent application Ser. No. 11/498,092, entitled“Systems and methods to transmit information among a plurality ofphysical upstream channels,” (Attorney Docket No. BP4911 or1875.8360001), filed Feb. 22, 2006, currently pending, and scheduledsubsequently to be issued as U.S. Pat. No. 8,335,226 on Dec. 18, 2012(as indicated in an ISSUE NOTIFICATION mailed from the USPTO on Nov. 28,2012), which claims priority pursuant to 35 U.S.C. §119(e) to thefollowing U.S. Provisional Patent Application which is herebyincorporated herein by reference in its entirety and made part of thepresent U.S. Utility Patent Application for all purposes:

-   -   1.1. U.S. Provisional Patent Application Ser. No. 60/704,898,        entitled “High upstream data rate while conserving transmit        power in multi-channel cable modem,” (Attorney Docket No. BP4911        or 1875.8360000), filed Aug. 3, 2005, now expired.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates generally to communication systems, andmore specifically to transmitting information among multiple physicalupstream channels in a communication system.

2. Description of Related Art

Communication systems include nodes that are coupled to each other viachannels. A channel need not necessarily have a physical structure. Forinstance, in many communication systems, a channel is defined by acarrier signal having a predetermined frequency. Communication systemsoften include at least one supervisory node and a plurality of remotenodes. Communications from a supervisory node to a remote node arereferred to as downstream communications and are transferred viadownstream channel(s). Communications from a remote node to asupervisory node are referred to as upstream communications and aretransferred via upstream channel(s).

Additive white Gaussian noise (AWGN) is often used to simulate orapproximate the noise that is associated with a channel. According tocommunications theory, channels operating in noise, such as AWGN, havetheoretical capacity limits. For example, the maximum data rate(R_(MAX)) associated with a channel is limited by the average transmitpower (P_(AVE)), the signal-to-noise ratio (SNR), the bandwidth for thechannel, and the upstream modulation technique. For a signal that ismodulated using digital symbols, the average transmit power and themodulation technique determine the maximum number of bits that may betransmitted per symbol. The SNR determines the minimum average transmitpower that is necessary to distinguish the signal from the AWGN. Thebandwidth determines the maximum number of symbols that may betransmitted per second. The maximum data rate of a channel may berepresented as R_(MAX)=X*Y, where X is the maximum number of bits thatmay be transmitted per symbol via the channel, and Y is the maximumnumber of symbols that may be transmitted per second via the channel.

In general, increasing the average transmit power by 3 dB enables anadditional bit of information per symbol to be transmitted for a givenSNR, bandwidth, and modulation technique, thereby increasing the maximumdata rate of the channel. However, increasing the average transmit powermay not be desirable due to any of a variety of reasons, including butnot limited to a) increased cost, b) lower reliability, c) increasednoise in adjacent and/or other channels, d) battery lifetime, and e)power limitations of the communication system.

Accordingly, systems and methods are needed that address one or more ofthe aforementioned shortcomings of conventional communication systemsand methods.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate embodiments of the present inventionand, together with the description, further serve to explain theprinciples of the invention and to enable a person skilled in thepertinent art(s) to make and use the invention.

FIG. 1 illustrates a high-level block diagram of an examplecommunication system according to an embodiment of the presentinvention.

FIGS. 2 and 3 are flowcharts of methods of transmitting a data sequencein accordance with embodiments of the present invention.

FIG. 4 illustrates a high-level block diagram of an example cable modemsystem according to an embodiment of the present invention.

FIG. 5 illustrates a schematic diagram of an example hybrid fibercoaxial (HFC) network showing pathways for data transmissions between aheadend and a plurality of cable modems according to an embodiment ofthe present invention.

FIG. 6 illustrates a block diagram of an example implementation of thecable modem termination system (CMTS) shown in FIG. 4 according to anembodiment of the present invention.

FIG. 7 illustrates a block diagram of an example implementation of thecable modem shown in FIG. 4 according to an embodiment of the presentinvention.

FIG. 8 illustrates an example implementation of the upstream burstmodulator shown in FIG. 7 according to an embodiment of the presentinvention.

FIG. 9 illustrates the performance of the cable modem system shown inFIG. 4 using a single physical upstream channel according to anembodiment of the present invention.

FIGS. 10-12 illustrate the performance of the cable modem system shownin FIG. 4 using two physical upstream channels according to respectiveembodiments of the present invention.

FIG. 13 illustrates the performance of the cable modem system shown inFIG. 4 using four physical upstream channels according to an embodimentof the present invention.

In the drawings, like reference numbers indicate identical orfunctionally similar elements. Additionally, the leftmost digit(s) of areference number identifies the drawing in which the reference numberfirst appears.

DETAILED DESCRIPTION OF THE INVENTION

This specification discloses one or more embodiments that incorporatethe features of this invention. The embodiment(s) described, andreferences in the specification to “one embodiment”, “an embodiment”,“an example embodiment”, etc., indicate that the embodiment(s) describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Furthermore, when a particularfeature, structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to effect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

1.0 Overview

FIG. 1 illustrates a high-level block diagram of an examplecommunication system 100 according to an embodiment of the presentinvention. In FIG. 1, communication system 100 includes a supervisorynode 102 and a remote node 104, which are connected via upstreamchannels 106 ₁-106 _(n) and downstream channel(s) 108. Supervisory node102 can be any of a variety of communication devices, including but notlimited to a cable modem termination system (CMTS), a satellite, or acellular base station. Remote node 104 can be any of a variety ofcommunication devices, including but not limited to a cable modem, asettop box, a cable gateway, a portable computing device, or a cellulartelephone.

Referring to FIG. 1, remote node 104 includes a remote transmittingmodule 116 and a remote receiving module 118. Remote transmitting module116 transmits an upstream transmission to supervisory node 102 viaupstream channels 106 ₁-106 _(n). Remote receiving module 118 receivesmessage(s) from supervisory node 102 via downstream channel(s) 108. Themessage(s) received by remote receiving module 118 determine the mannerin which remote transmitting module 116 transmits a data sequence tosupervisory node 102. A data sequence can be a singular data sequence ora plurality of data sequences.

Supervisory node 102 includes a supervisory receiving module 110, amonitoring module 112, and a supervisory transmitting module 114.Supervisory receiving module 110 receives the upstream transmission fromremote transmitting module 116. Monitoring module 112 monitors acharacteristic associated with communication system 100. For example,monitoring module 112 may monitor an aggregate upstream power or anaggregate upstream bandwidth of communication system 100. In anotherexample, monitoring module 112 may monitor a signal-to-noise ratio(SNR), an error rate (e.g., packet, symbol, code word, pre-FEC,post-FEC, etc.), a data rate, or an average transmit power of theupstream transmission that supervisory receiving module 110 receivesfrom remote node 104. Accordingly, in the embodiment of FIG. 1,monitoring module 112 is shown to be optionally coupled to supervisoryreceiving module 110. The characteristic monitored by monitoring module112 may be based on any of a variety of factors, including but notlimited to those mentioned above or a combination thereof.

Supervisory transmitting module 114 is configured to transmit a firstdownstream message to remote node 104 based on the characteristic thatis monitored by monitoring module 112. For instance, supervisorytransmitting module 114 may transmit the first downstream message inresponse to the characteristic reaching a first threshold. If thecharacteristic is based on a plurality of factors, then the firstthreshold may include a plurality of thresholds associated withrespective factors. Threshold(s) of one or more factors may be dependenton the value(s) of other factor(s). For example, thresholds associatedwith first and second factors may be mutually dependent, meaning thatthe threshold of the first factor is dependent on the value of thesecond factor and the threshold of the second factor is dependent on thevalue of the first factor. The first threshold may be predetermined,though the scope of the present invention is not limited in thisrespect. As described above, the first threshold may be variable.

The first downstream message indicates the manner in which remote node104 is to transmit a data sequence. For example, the message mayindicate the number of upstream channels 106 ₁-106 _(n) that remotetransmitting module 116 is to use for transmitting the data sequence tosupervisory node 102. In this example, remote transmitting module 116 isconfigured to transmit at least a first portion of the data sequenceamong N upstream channels 106 ₁-106 _(n) at a cumulative first data rateusing a cumulative first average transmit power based on the firstdownstream message. The cumulative first data rate is the sum of thedata rates associated with the respective N upstream channels 106 ₁-106_(n). The cumulative first average transmit power is the sum of theaverage transmit powers associated with the respective N upstreamchannels 106 ₁-106 _(n).

The cumulative first average transmit power is no greater than a secondaverage transmit power that would be necessary to transmit the datasequence at a second data rate that is less than the cumulative firstdata rate using M upstream channels 106 ₁-106 _(n), wherein N>M≧1.Accordingly, remote transmitting module 116 transmits at least the firstportion of the data sequence at an average transmit power that is nogreater than the average transmit power necessary to transmit the datasequence at a lower data rate using fewer upstream channels. In anaspect, configuring remote transmitting module 116 in this mannerenables remote transmitting module 116 to transmit at least the firstportion of the data sequence at a greater data rate without increasingthe average transmit power.

According to an embodiment, supervisory transmitting module 114 isfurther configured to transmit a second downstream message based on thecharacteristic reaching a second threshold. In this embodiment, remotetransmitting module 116 is further configured to transmit a secondportion of the data sequence using M upstream channels 106 ₁-106 _(n) atthe second data rate using the second average transmit power based onthe second downstream message. The first and second thresholds may bethe same or different.

Persons skilled in the relevant art(s) will recognize that supervisorynode 102 need not necessarily include monitoring module 112. Forexample, remote node 104 may include monitoring module 112.

FIGS. 2 and 3 illustrate flowcharts 200 and 300 of methods oftransmitting a data sequence in accordance with embodiments of thepresent invention. The invention, however, is not limited to thedescription provided by flowcharts 200 and 300. Rather, it will beapparent to persons skilled in the relevant art(s) from the teachingsprovided herein that other functional flows are within the scope andspirit of the present invention.

Flowcharts 200 and 300 will be described with continued reference toexample communication system 100 described above in reference to FIG. 1,though the methods are not limited to that embodiment.

Referring now to FIG. 2, a characteristic associated with acommunication system is monitored at block 202. For example, monitoringmodule 112 may monitor the characteristic. Persons skilled in therelevant art(s) will recognize that any of a variety of means maymonitor the characteristic at block 202, including but not limited to aCMTS, a satellite, a cellular base station, or a component thereof.

At least a first portion of the data sequence is transmitted among Nphysical upstream channels at a cumulative first data rate using acumulative first average transmit power based on the characteristic atblock 204. The cumulative first average transmit power is less than orequal to a second average transmit power that is necessary to transmitthe data sequence at a second data rate that is less than the cumulativefirst data rate using M physical upstream channels, wherein N>M≧1. Forexample, remote transmitting module 116 may transmit at least the firstportion of the data sequence. Other exemplary means for transmitting atleast the first portion of the data sequence include but are not limitedto a cable modem, a settop box, a cable gateway, a portable computingdevice, a cellular telephone, or a component thereof.

At block 204, transmitting at least the first portion of the datasequence may be performed in accordance with a communication standardsuch as a Data Over Cable Service Interface Specification (DOCSIS™)standard, an Institute of Electrical and Electronics Engineers (IEEE)802.11 standard, a cellular communication standard, etc. The operationat block 204 may be performed in response to the characteristic reachinga threshold, though the scope of the present invention is not limited inthis respect.

Referring now to FIG. 3, a characteristic associated with acommunication system is monitored at block 202. If the characteristicdoes not reach a first threshold, as determined at decision block 302,then the characteristic continues to be monitored at block 202. Forinstance, monitoring module 112 may perform the monitoring anddetermining operations at respective blocks 202 and 302. Changes,modifications, or adjustments to remote node 104 and/or some otherremote node(s) may occur to adjust the monitored characteristic and/orthe first threshold. For instance, an error rate, SNR, etc. may bemonitored until a desired value is achieved. If the characteristicreaches the first threshold, as determined at block 302, then a firstdownstream message is transmitted at block 304. For example, supervisorytransmitting module 114 may transmit the first downstream message. Thefirst downstream message may be a data grant message, for example,granting permission for remote node to transmit the data sequence.

At least a first portion of the data sequence is transmitted among Nphysical upstream channels at a cumulative first data rate using acumulative first average transmit power based on the first downstreammessage at block 306. The cumulative first average transmit power isless than or equal to a second average transmit power that is necessaryto transmit the data sequence at a second data rate that is less thanthe cumulative first data rate using M physical upstream channels,wherein N>M≧1.

The method described herein with reference to flowchart 300 mayoptionally include the operations depicted by blocks 308, 310, and 312.The method need not necessarily include operations 308, 310, and 312.Referring to FIG. 3, if the characteristic does not reach a secondthreshold, as determined at decision block 308, then the data sequencecontinues to be transmitted among N physical upstream channels at block306. For instance, monitoring module 112 may perform the determiningoperation at block 308. If the characteristic reaches the secondthreshold, as determined at block 308, then a second downstream messageis transmitted at block 310. For example, supervisory transmittingmodule 114 or any of a variety of other means including but not limitedto a CMTS, a satellite, a cellular base station, or a component thereofmay transmit the second downstream message. The second downstreammessage is provided to change the manner in which the data sequence istransmitted upstream.

The data sequence continues transmission using M physical upstreamchannels at the second data rate using the second average transmit powerbased on the second downstream message at block 312. For example, remotetransmitting module 116 or any of a variety of other means including butnot limited to a cable modem, a settop box, a cable gateway, a portablecomputing device, a cellular telephone, or a component thereof maytransmit the second downstream message.

2.0 Example Cable Modem System Embodiments

Although the embodiments of the invention described below with referenceto FIGS. 4-11 refer specifically, and by way of example, to cable modemsystems, including cable modem termination systems and cable modems, itwill be readily apparent to persons skilled in the relevant art(s) thatthe invention is equally applicable to other communication systems,including but not limited to satellite systems, optical communicationssystems, telephone wire systems, wireless networking systems, cellularsystems, and/or any combination thereof. In these embodiments,supervisory node 102 is shown to be a cable modem termination system(CMTS), and remote node 104 is shown to be a cable modem. However, suchlabeling is not intended to limit the scope of the invention. It willalso be readily apparent to persons skilled in the relevant art(s) thatthe invention is applicable to any point-to-multipoint system.

A cable modem system typically includes a headend that is capable ofcommunicating with multiple CPE, each of which provides cable modemfunctionality. The CPE may be a cable modem, a settop box, or a cablegateway, to provide some examples. The upstream of the cable modemsystem may consist of multiple channels that can be assigned to themultiple CPE. These channels are separated from each other by operatingat different frequencies. The downstream traditionally consists of asingle broadcast channel. However, embodiments of the present inventionare applicable to cable modem systems (or any other communicationsystem) having multiple downstream channels.

DOCSIS™ (Data Over Cable Service Interface Specification) refers to agroup of specifications published by CableLabs® that define industrystandards for cable headend and cable modem equipment. In part, DOCSIS™sets forth requirements and objectives for various aspects of cablemodem systems including operations support systems, management, datainterfaces, as well as network layer, data link layer, and physicallayer transport for data over cable systems. The current version of theDOCSIS™ specification is version 2.0, and includes the DOCSIS™ RadioFrequency Interface (RFI) Specification SP-RFIv2.0-103-021218(hereinafter “DOCSIS™ RFI Specification”), the entirety of which isincorporated by reference herein.

2.1 Example Cable Modem System

FIG. 4 illustrates a high-level block diagram of an example cable modemsystem 400 according to an embodiment of the present invention. Cablemodem system 400 enables voice communications, audio communications,data services, video, messaging, graphics, other forms of media and/ormultimedia, or any combination thereof, based on a bi-directionaltransfer of packet-based traffic, such as Internet Protocol (IP)traffic.

Referring to FIG. 4, the bi-directional transfer of packet-based trafficoccurs between a cable system headend 404 and a plurality of cablemodems 104 ₁-104 _(p) via a communication network 406, which, by way ofexample, may comprise a hybrid fiber coaxial (HFC) network.Communication network 406 may support wired, wireless, or bothtransmission media, including satellite, terrestrial (e.g., fiber optic,copper, twisted pair, coaxial, etc.), radio, microwave, free-spaceoptics, and/or any other form or method of transmission. In anembodiment, communication network 406 includes frequency translationdevices in support of a frequency stacking architecture.

Cable headend 404 generally includes at least one cable modemtermination system (CMTS) 102. CMTS 102 is a portion of cable headend404 that manages the upstream and downstream transfer of data betweencable headend 404 and cable modems 104 ₁-104 _(p), each of which may belocated at respective customer premises. CMTS 102 broadcasts informationdownstream to cable modems 104 ₁-104 _(p) as a continuous transmittedsignal in accordance with a time division multiplexing (TDM) technique.The downstream signal may be formatted with a motion picture expertgroup (MPEG) transmission convergence sublayer, though the presentinvention is not limited in this respect. For instance, embodiments ofthe present invention may be configured to support other data formats aswould be apparent to one skilled in the relevant art(s).

Additionally, CMTS 102 receives data from cable modems 104 ₁-104 _(p)over a plurality of shared upstream channels. Data from cable modems 104₁-104 _(p) is transmitted upstream in accordance with a time domainmultiple access (TDMA) technique or a synchronous code division multipleaccess (S-CDMA) technique.

CMTS 102 establishes the upstream slot structure and allocates upstreambandwidth by sending, for example, an upstream channel descriptor (UCD)message and MAP messages, respectively, to cable modems 104 ₁-104 _(p).CMTS 102 also uses the MAP messages and slot count values to anticipateburst arrivals from cable modems 104 ₁-104 _(p). In an embodiment, theUCD and MAP messages are defined by the DOCSIS™ specification,originated by CableLabs®, which specifies the interface requirements forcable modem systems.

According to an embodiment, CMTS 102 connects to up to four adjacent,six mega-Hertz (MHz) carriers, each of which taken individually is acompletely DOCSIS™2.0-compliant downstream. Carriers connected to CMTS102 need not necessarily be adjacent. It should be understood that thequantity of carriers and the carrier specifications may vary asdetermined by the system architect. For example, a plurality of eightMHz carriers may be connected to CMTS 102 to conform with Europeanstandards.

As shown in FIG. 4, CMTS 102 further serves as an interface betweencommunication network 406 and a packet switched network 402,transferring packets received from cable modems 104 ₁-104 _(p) to packetswitched network 402 and transferring packets received from packetswitched network 402 to cable modems 104 ₁-104 _(p) when appropriate.

Packet switched network 402 is part of a wired, wireless, or combinationof wired and wireless local area networks (LANs), wide area networks(WANs), and/or optical networks (e.g., an organization's intranet, localinternets, the global-based Internet (including the World Wide Web(WWW)), virtual private networks, and/or the like). CMTS 102 utilizespacket switched network 402 to communicate with another device orapplication external to cable modem system 400. The device orapplication may be a server, web browser, operating system, other typesof information processing software (e.g., word processing, spreadsheets,financial management, or the like), television or radio transmitter,another cable modem 104, another CMTS 102, or the like.

In addition to CMTS 102, cable headend 404 may include one or morerouters to facilitate the connection between CMTS 102 and packetswitched network 402, as well as one or more servers for performingnecessary network management tasks. Headend 404 may also include one ormore satellite receivers, video modulators, and/or telephone switches,to provide other examples.

Each of cable modems 104 ₁-104 _(p) operates as an interface betweencommunication network 406 and a corresponding attached user device 408₁-408 _(p). In particular, each cable modem 104 ₁-104 _(p) convertsdownstream signals received over communication network 406 into IP datapackets to be received by a corresponding attached user device 408 ₁-408_(p). Cable modems 104 ₁-104 _(p) are configurable to transport one ormore services to user devices 408 ₁-408 _(p). The services may includebut are not limited to telephony, television broadcasts, pay-for-view,Internet communications (e.g., WWW), radio broadcasts, facsimile, filedata transfer, electronic mailing services (email), messaging, videoconferencing, live or time-delayed media feeds (such as, speeches,debates, presentations, infomercials, news reports, sporting events,concerts, etc.), and/or the like.

Additionally, each cable modem 104 ₁-104 _(p) converts IP or othersuitable protocols (e.g., asynchronous transfer mode (ATM)) forpacketized data received from a corresponding user device 408 ₁-408 _(p)into upstream burst signals suitable for transfer over communicationnetwork 406. The upstream is divided into one or more upstream channels.Each upstream channel carries bursts of packets from cable modems 104₁-104 _(p) to CMTS 102. In the upstream, each channel is broken intomultiple assignable slots, and cable modems 104 ₁-104 _(p) send a burstsignal in an assigned slot. As discussed above, the slot structure isdefined and assigned by CMTS 102.

CMTS 102 is capable of assigning upstream burst signals of a cable modem104 to slots that are spread among a plurality of upstream channels,thereby enabling the cable modem 104 to transmit on multiple upstreamchannels simultaneously. The cable modem 104 transmits the upstreamburst signals among the slots in accordance with the slot assignmentsprovided by CMTS 102. This technique of bonding together smallerbandwidth upstream channels to create a larger bandwidth pipe isreferred to herein as “channel bonding”. Exemplary channel bondingtechniques are described in U.S. Patent application Ser. No. 11/298,446(U.S. Pub. No. 2006/0126660), filed Dec. 12, 2005, which is incorporatedherein by reference in its entirety.

Devices or equipment that are not capable of handling upstream channelbonding include, for example, “legacy cable modems.” As such,embodiments of the present invention may fully integrate the operationand/or management of legacy devices and devices that are capable ofupstream channel bonding, both having the ability to communicate withinthe same communication system.

Referring to FIG. 4, each cable modem 104 ₁-104 _(p) is shown supportingonly a single user device for the sake of clarity. However, each cablemodem 104 ₁-104 _(p) is generally capable of supporting a plurality ofuser devices for communication over cable modem system 400. A userdevice may be a personal computer, data terminal equipment, telephonydevice, broadband media player, network controlled appliance, or anyother device capable of transmitting or receiving data over a packetswitched network.

According to an embodiment, CMTS 102 and cable modems 104 ₁-104 _(p) areintegrated to support protocols such as Internet Protocol (IP),Transmission Control Protocol (TCP), User Datagram Protocol (UDP), RealTime Transport Protocol (RTP), Resource Reservation Protocol (RSVP),etc.

In an embodiment, cable modems 104 ₁-104 _(p) and CMTS 102 representDOCSIST™-compliant cable modem equipment. In other words, cable modems104 ₁-104 _(p) and CMTS 102 are adapted to communicate in accordancewith protocols and/or formats provided in the DOCSIS™ specification.

FIG. 5 illustrates a schematic diagram of an example hybrid fibercoaxial (HFC) network 500 to facilitate transmission of data betweenheadend 404 and cable modems 104 ₁-104 _(p) according to an embodimentof the present invention. For example, communication network 406 isoften used by a cable provider to provide Internet access, cabletelevision, and/or pay-per-view programming to subscribers.

In FIG. 5, approximately 500 cable modems 104 are in electricalcommunication with each node 520 of communication network 406 forillustrative purposes. In the embodiment of FIG. 5, cable modems 104 areconnected to a node 520 via coaxial cables 530. Communication network406 includes amplifiers 540 to facilitate the electrical connection ofthe more distant cable modems 104, for example, to nodes 520. Amplifyingthe electrical signals may desirably enhance the signal-to-noise ratio(SNR) of communications between headend 404 and cable modems 104.Coaxial cables 530 a-530 d electrically connect cable modems 104 withcoaxial cables 530 f, 530 g, which extend between amplifiers 540 andnodes 520.

Each node 520 is electrically connected to a hub 550, typically via anoptical fiber 560. Hubs 550 are in communication with headend 404 viaoptical fibers 570. Each hub 550 is generally capable of facilitatingcommunication with 20,000 cable modems 104.

Optical fibers 570 extending intermediate headend 404 and each hub 550define a fiber ring, which is typically capable of facilitatingcommunication between approximately 100,000 cable modems 104 and headend404. Headend 404 may communicate via transmission line 580 with theInternet, another headend, and/or any other suitable device(s) ornetwork. Transmission line 580 may be a T1 line or a T2 line, to providesome examples.

FIG. 6 illustrates a block diagram of an exemplary implementation ofCMTS 102 of cable modem system 400 according to an embodiment of thepresent invention. This exemplary implementation is presented by way ofexample, and is not intended to limit the scope of the presentinvention. CMTS 102 processes signals both at a physical (PHY) layer andat a media access control (MAC) layer. CMTS 102 includes a CMTS MAC 610,which provides hardware support for MAC layer per-packet functions, suchas fragmentation, concatenation, payload header suppression/expansion,and/or error checking. Providing such support reduces the amount ofprocessing required of a system central processing unit (CPU) 620, whichserves to improve the overall performance of CMTS 102.

An upstream processor 612 of CMTS MAC 610 performs data encryptionstandard (DES) decryption, fragment reassembly, de-concatenation,payload packet expansion, packet acceleration, upstream managementinformation base (MIB) statistic gathering, and/or priority queuing forthe resultant packets. Each output queue is independently configured toprovide packets to a peripheral component interconnect (PCI) or agigabit media independent interface (GMII) (not shown).

A downstream processor 614 of CMTS MAC 610 accepts packets from priorityqueues and performs payload header suppression, DOCSIS™ header creation,DES encryption, cyclic redundancy checking (CRC), header check sequencecreation in accordance with the DOCSIS™ specification, Moving PicturesExperts Group (MPEG) encapsulation, and/or multiplexing. In anembodiment, a downstream synchronous dynamic random access memory SDRAM630 is used to support packaging, handling, and storage of output queuesreceived from CMTS MAC 610.

A memory 692 may interact with CMTS MAC 610 to store signals as they areprocessed by CMTS MAC 610. Memory 692 may also store various auxiliarydata used to support processing activities of CMTS MAC 610. Suchauxiliary data may include but is not limited to security protocols,identifiers, rules, policies, or the like, as described in greaterdetail below.

According to an embodiment, memory 692 stores a software application tooperate on one or more processors or hardware assist devices, such as afield-programmable gate array (FPGA) or an application-specificintegrated circuit (ASIC). For instance, the one or more processors mayuse the software application to process control messages, voice, and/ordata received from CMTS MAC 610. In an embodiment, the softwareapplication includes a classifier/router and a bandwidth (BW) allocationcontroller. The BW allocation controller manages upstream and/ordownstream modulation and bandwidth allocation. The classifier/routerprovides rules and policies for classifying and/or prioritizingcommunications with cable modems 104. The classifier/router also routessignals from cable modems 104 to a destined location over packetswitched network 402.

In an embodiment, CMTS MAC 610 is configured and managed externally viaa PCI interface (not shown) and a PCI bus 640. Alternatively, CMTS MAC610 may be operated remotely using a routing/classification engine 650that is located externally to CMTS MAC 610.

According to an embodiment, first and second upstream SDRAMs 660 areused to minimize latency on the internal buses of CMTS 102. For example,in an embodiment, first upstream SDRAM 660 a is operable to support keysand reassembly, and second upstream SDRAM 660 b is operable to supportpacket header suppression (PHS) and output queues.

A Serial Peripheral Interface (SPI) master port (not shown) is employedto control the interface between MAC layer components and PHY layercomponents. For example, the SPI master port may be used to control theinterface between the CMTS MAC 610 and the upstream receiver 670 and/orbetween the CMTS MAC 610 and downstream modulator 680.

CMTS MAC 610 generates data which is modulated and then transmitted toone or more cable modems 104. For example, data generated by CMTS MAC610 is modulated onto a carrier signal by downstream modulator 680 andthen transmitted downstream by downstream transmitter 690. Upstreamreceiver 670 receives information from cable modems 104 in bursts ofTDMA- or S-CDMA-encoded packets.

Network controller 694 configures upstream receiver 670 for a bandwidthand informs upstream receiver 670 of the nominal power of communicationsthat are to be received at upstream receiver 670, unless upstreamreceiver 670 is hard-wired to know the nominal power.

In the embodiment of FIG. 6, network controller 694 includes scheduler696, status module 698, and monitoring module 112. Monitoring module 112monitors a characteristic associated with upstream burst signalsreceived at upstream receiver 670. Monitoring module 112 providesinformation regarding the characteristic to scheduler 696. CMTS MAC 610provides to scheduler 696 a request for upstream capacity. Scheduler 696determines the upstream grant, which includes upstream minislotassignments, channels, and burst profiles for upstream communicationsbased on the information regarding the characteristic and the requestfor upstream capacity. Scheduler 696 provides the upstream grantinformation to CMTS MAC 610, which forwards the grant information todownstream modulator 680. Upstream receiver 670 receives the grantinformation from CMTS MAC 610 or network controller 694, so thatupstream receiver 670 is prepared to receive the upstreamcommunications.

Downstream modulator 680 modulates the grant information onto a carriersignal, so that downstream transmitter 690 may transmit the resultingMAP message and/or UCD message to cable modem 104. Status module 698stores information regarding the MAP messages and/or UCD message thatare sent to cable modem 104. For example, this information may includeburst profiles that have been provided to cable modem 104 regarding theupstream channels, user-unique power levels sent to cable modem 104,and/or user-unique frequency assignments for cable modem 104.

FIG. 7 illustrates a block diagram of an exemplary implementation ofcable modem 104 of cable modem system 400 according to an embodiment ofthe present invention. This exemplary implementation is presented by wayof example, and is not intended to limit the present invention. Cablemodem 104 is configured to receive and transmit signals to and fromcommunication network 406 via coaxial connector 705. Accordingly, cablemodem 104 will be described in terms of a receiver portion and atransmitter portion.

The receiver portion includes a diplex filter 710, a radio frequency(RF) tuner 715, a surface acoustic wave (SAW) filter 720, an amplifier725, and a downstream receiver 730. Reception begins with diplex filter710 receiving a downstream signal originating from CMTS 102. Diplexfilter 710 isolates the downstream signal and routes the signal to RFtuner 715. In an embodiment, the downstream signal has spectralcharacteristics in the frequency range of approximately 54-860 MHz. RFtuner 715 downconverts the signal and provides the downconverted signalto SAW filter 720, which passes only spectral components of thedownconverted signal that are within a particular bandwidth. Amplifier725 amplifies the filtered signal and passes it to downstream receiver730. According to an embodiment, automatic gain controls are providedfrom downstream receiver 730 to RF tuner 715.

Downstream receiver 730 demodulates the amplified signal. For example,downstream receiver 730 may demodulate the amplified signal inaccordance with a quadrature amplitude modulation (QAM) technique, suchas 64-QAM or 256-QAM, to recover the underlying information signal.Downstream receiver 730 also converts the underlying information signalfrom an analog form to digital form. Downstream receiver 730 thenprovides the digitized underlying information to a media access control(MAC) 735.

MAC 735 processes the digital data, which may include, for example,Ethernet packets for transfer to an attached user device. The functionsof MAC 735 are implemented in hardware, software, firmware, or acombination thereof. In the example implementation of FIG. 7, thefunctions of MAC 735 are implemented in both hardware and software.Random access memory (RAM) 755 and/or read-only memory (ROM) 760 storessoftware functions of MAC 735. CPU 750 executes the software functionsof MAC 735. MAC 735 is in electrical communication with CPU 750, RAM755, and ROM 760 via a shared communications medium 740. Sharedcommunications medium 740 may include a computer bus or a multipleaccess data network, to provide some examples.

Referring to FIG. 7, MAC 735 is further in electrical communication withan Ethernet interface 745 via shared communications medium 740. Whenappropriate, MAC 735 transfers Ethernet packets received from downstreamreceiver 730 to Ethernet interface 745 for transfer to an attached userdevice.

The transmitter portion of cable modem 104 includes an upstream burstmodulator 765, a low pass filter 770, a power amplifier 775, and diplexfilter 710. Transmission begins with MAC 735 receiving a data packet.According to an embodiment, the data packet includes data originallyreceived from an attached user device via Ethernet interface 745. Inanother embodiment, MAC 735 generates the data packet as part of thecable modem network management and upkeep. MAC 735 formats the datapacket in compliance with the protocols set forth in the DOCSIS™specification. MAC 735 provides the data packet to upstream burstmodulator 765, which converts the data packet into analog form andmodulates the data packet onto a carrier signal in accordance with aparticular modulation technique. The modulation technique may include,without limitation, a Quadrature Phase Shift Key (QPSK) technique, an8-QAM technique, a 16-QAM technique, a 32-QAM technique, or a 64-QAMtechnique, to provide some examples.

Upstream burst modulator 765 provides the modulated carrier signal tolow pass filter (LPF) 770, which generally passes signals with spectralcharacteristics in a desired bandwidth within the frequency range ofapproximately 5-42 MHz. Power amplifier 775 amplifies the filteredsignal received from LPF 770 and provides the amplified signal to diplexfilter 710. Upstream burst modulator 765 typically regulates the gain ofpower amplifier 775. Diplex filter 710 isolates the amplified signal andtransmits the amplified signal upstream over communication network 406during a scheduled burst opportunity.

According to an embodiment, MAC 735 includes an upstream portion and adownstream portion. The downstream portion of MAC 735 receives grantinformation from downstream receiver 730 and forwards the grantinformation to cable modem controller 780. Cable modem controller 780provides the grant information to upstream burst modulator 765 toconfigure upstream burst modulator 765 for transmission of the upstreamcommunications. Cable modem controller 780 further provides the grantinformation to the upstream portion of MAC 735. For transmissionsinvolving a plurality of upstream channels, MAC 735 facilitates bondingof the upstream channels. For example, MAC 735 may bond N upstreamchannels, enabling upstream burst modulator 765 to transmit at least afirst portion of an upstream communication among the N upstream channelsat a cumulative data rate using a cumulative average transmit power thatis less than the average transmit power that would be necessary totransmit the upstream communication at the same data rate or a lowerdata rate using fewer upstream channels.

In another embodiment, cable modem controller 780 includes monitoringmodule 112, which monitors a characteristic of communication system 100.For example, cable modem controller 780 may provide information to MAC735 and/or upstream burst modulator 765, indicating that upstreamcommunication is to be transmitted using bonded upstream channels inresponse to the characteristic satisfying a condition (e.g., reaching athreshold).

FIG. 8 illustrates an example implementation of upstream burst modulator765 of FIG. 7 according to an embodiment of the present invention. InFIG. 8, upstream burst modulator 765 is implemented as a plurality ofupstream burst modulators 765 a-d that are coupled in parallel with eachother. Each upstream burst modulator 765 a-d is operated independently.For instance, network controller 694 of CMTS 102 (see FIG. 6) mayallocate burst grants to respective upstream burst modulators 765 a-dindependently.

It should be noted that the total upstream power provided by cable modem104 is a limited resource. Accordingly, the cumulative upstream powerassociated with upstream burst modulators 765 a-d cannot exceed thelimits of cable modem system 400. This upstream power limitation maynecessitate that upstream burst modulators 765 a-d be operated with somelevel of dependency.

2.2 Example System Performance

FIGS. 9-13 are provided to illustrate the performance of cable modemsystem 400 shown in FIG. 4 according to embodiments of the presentinvention. The performance in each figure is shown with average transmitpower (P) along the Y axis and frequency (f) along the X axis. Thepowers shown along the Y axes are represented linearly, as opposed tothe traditional logarithmic representation, to more clearly illustratethe differences between the figures. In the discussion of FIGS. 9-13,cable modem 104 is assumed to be “non-disadvantaged”, i.e., capable ofoperating a single channel in accordance with a 64-Quadrature AmplitudeModulation (64QAM) technique. Data rates are represented as“unburdened”, i.e., not including FEC parity, time guard bands, MAC,etc.

2.2.1 Single Upstream Channel

FIG. 9 illustrates the performance of cable modem system 400 using asingle physical upstream channel according to an embodiment of thepresent invention. Referring to FIG. 9, cable modem 104 transmits anupstream communication using a 64QAM technique in a single 6.4 MHzchannel. Cable modem 104 utilizes an average transmit power of P₀. Inthe description of FIGS. 9-13, P₀=+52 dBmV for illustrative purposes.However, persons skilled in the relevant art(s) will recognize that P₀may be any value. For illustrative purposes, assume that P₀=+52 dBmVenables cable modem 104 utilizing 64QAM to transmit 6 bits/symbolupstream. Accordingly, in the embodiment of FIG. 9, cable modem 104provides an unburdened upstream capacity R₉ of approximately 30 Mbps, asshown by the following equation:

$R_{9} = {{6\frac{bits}{symbol}*5.12\frac{{Msymbols}/\sec}{channel}*1\mspace{14mu} {channel}} \approx {30\mspace{14mu} {{Mbps}.}}}$

In general, each additional 3 dB of average transmit power enables cablemodem 104 to provide approximately one additional bit per symbol in anupstream transmission. Accordingly, doubling the average transmit powerin FIG. 9 to P=2*P₀=+55 dBmV provides an unburdened upstream capacityR₉′ of approximately 35 Mbps, utilizing the single physical upstreamchannel:

$R_{9}^{\prime} = {{7\frac{bits}{symbol}*5.12\frac{{Msymbols}/\sec}{channel}*1\mspace{14mu} {channel}} \approx {35\mspace{14mu} {{Mbps}.}}}$

2.2.2 Two Upstream Channels

FIGS. 10-12 illustrate the performance of cable modem system 400 usingtwo physical upstream channels according to respective embodiments ofthe present invention.

Referring to FIG. 10, cable modem 104 transmits an upstreamcommunication using a 64QAM technique across two 6.4 MHz channels. Cablemodem 104 utilizes an average transmit power of P₀ for each channel,providing a total average transmit power P_(TOTAL) of 2*P₀=+55 dBmV.Using two physical upstream channels enables cable modem 104 to transmit2 symbols of 6 bits each simultaneously, providing an unburdenedupstream capacity R₁₀ of approximately 60 Mbps, as shown by thefollowing equation:

$R_{10} = {{6\frac{bits}{symbol}*5.12\frac{{Msymbols}/\sec}{channel}*2\mspace{14mu} {channels}} \approx {60\mspace{14mu} {{Mbps}.}}}$

In this example embodiment, using two physical upstream channelsprovides a 25 Mbps improvement in unburdened upstream capacity, ascompared to using a single physical upstream channel at the same averagetransmit power.

FIG. 11 shows that spreading an upstream communication among morephysical upstream channels can provide a greater unburdened upstreamcapacity without requiring an increase of average transmit power. Forexample, in FIG. 11, cable modem 104 transmits an upstream communicationusing 32QAM across two 6.4 MHz channels. Utilizing an average transmitpower of +49 dBmV for each channel (i.e., P_(TOTAL)=+52 dBmV) enablescable modem 104 to transmit 5 bits/symbol in each channel, providing anunburdened upstream capacity R₁₁ of approximately 50 Mbps:

$R_{11} = {{5\frac{bits}{symbol}*5.12\frac{{Msymbols}/\sec}{channel}*2\mspace{14mu} {channels}} \approx {50\mspace{14mu} {{Mbps}.}}}$

Thus, using the techniques provided herein, the “non-disadvantaged” CMcan almost double its upstream data rate (from approximately 30 Mbps to50 Mbps), without requiring increased average transmit power.

Enabling one channel at 64QAM with maximum upstream transmit power,DOCSIS™ 2.0 provides approximately 30 Mbps unburdened upstream datacapacity. In contrast, according to the techniques described herein,enabling two 5 bits/symbol channels with the same total power providesapproximately 50 Mbps unburdened upstream capacity. Note that anadditional 3 dB of transmit power capability would only provide anadditional 10 Mbps (from 50 to 60 Mbps) of capacity in the two channels.For a single cable modem, once a high SNR is reached, spreading energyover more bandwidth or dimensions provides higher capacity thanconcentrating more energy in fewer dimensions. For example, anembodiment that utilizes four physical upstream channels to provide evenhigher capacity is discussed below with reference to FIG. 13, followingthe discussion of FIG. 12.

FIG. 12 shows that spreading an upstream communication among morephysical upstream channels can provide a greater unburdened upstreamcapacity at a lower average transmit power. Referring to FIG. 12, cablemodem 104 transmits an upstream communication using 16QAM across two 6.4MHz channels. Utilizing an average transmit power of +46 dBmV for eachchannel (i.e., P_(TOTAL)=+49 dBmV) enables cable modem 104 to transmit 4bits/symbol in each channel, providing an unburdened upstream capacityR₁₂ of approximately 40 Mbps:

$R_{12} = {{4\frac{bits}{symbol}*5.12\frac{{Msymbols}/\sec}{channel}*2\mspace{14mu} {channels}} \approx {40\mspace{14mu} {{Mbps}.}}}$

As compared to the single physical upstream channel embodiment describedabove with respect to FIG. 9, the embodiment of FIG. 12 provides agreater upstream data rate (40 Mbps versus 30 Mbps), even though theembodiment of FIG. 9 requires more average transmit power (52 dBmVversus 49 dBmV).

If other cable modems can operate on the two physical upstream channelsusing a 64QAM technique because they have less insertion loss to theupstream receiver, then cable modem system 400 may lose some capacity byallocating approximately 12 MHz of channels for 16QAM operation (asopposed to 64QAM operation), even though the above usage scheme mayoptimize the upstream bursting communications for cable modem 104. Thisis one “cost” imposed upon cable modem system 400 for givingpower-limited cable modems higher burst rate and for not burdening everycable modem with a higher cost for peak power. By allowing the twophysical upstream channels to be used in 64QAM mode when other userswith less insertion loss up to the receiver are transmitting via logicalchannels, additional burst profiles, etc., cable modem system 400reduces the lost capacity in those channels.

2.2.3 Four Upstream Channels

FIG. 13 illustrates the performance of cable modem system 400 using fourphysical upstream channel according to an embodiment of the presentinvention. In the embodiment of FIG. 13, cable modem 104 transmits anupstream communication using a 16QAM technique across four 6.4 MHzchannels. Cable modem 104 utilizes +46 dBmV of average transmit powerfor each channel, providing a total average transmit power P_(TOTAL) of+52 dBmV. Cable modem 104 transmits 4 bits/symbol in each channel,providing an unburdened upstream capacity R₁₃ of approximately 80 Mbps:

$R_{13} = {{4\frac{bits}{symbol}*5.12\frac{{Msymbols}/\sec}{channel}*4\mspace{14mu} {channels}} \approx {80\mspace{14mu} {{Mbps}.}}}$

Utilizing four physical upstream channels enables cable modem 104 tomore than double the unburdened upstream capacity described with respectto the single physical upstream channel embodiment of FIG. 9 withoutincreasing the required average transmit power.

Operating cable modem 104 in four 6.4 MHz upstream channels introduces a“cost” to cable modem system 400, because cable modem 104 is using theupstream channels at 16QAM when other cable modems may be able totransmit in those channels using more power (especially if only usingone of them) and achieve more bits/sec per Hz in overall upstreamcapacity for cable modem system 400.

Out-of-band spurious performance is another consideration. Increasingthe maximum average transmit power of cable modems runs counter totightening the out-of-band spurious requirements, which facilitatestotal upstream system capacity by preserving channels for high densityoperation. For example, it may not be desirous for DOCSIS™ transmittersto raise the noise floor of clean channels, which would otherwisesupport 256QAM. Supporting 256QAM likely will provide greater totalnetwork capacity than will enabling a few weak modems with a dozen or somore Mbps at the expense of increased cost for all cable modems and moreout-of-band spurious energy.

In other words, allocating a high burst rate in too few channels (e.g.,a single channel) can “cost” cable modem system 400 in terms of totalthroughput. It may not be desirous for a “disadvantaged” cable modem(i.e., a cable modem with a large insertion loss to upstream receiver)to be empowered with more transmit power at the increased cost of allcable modems in order to realize a minimal benefit in its upstreamthroughput. “Non-disadvantaged” cable modems, however, do not need moretransmit power to realize substantial increases in throughput when morebandwidth (e.g., more channels) is available.

A “disadvantaged” cable modem, supporting two upstream channels, both atmaximum average transmit power, is counter to the more efficientapproach of using fewer spreading codes for disadvantaged users affordedby SCDMA (or more narrow channel bandwidth for TDMA users). On the otherhand, for a “non-disadvantaged” cable modem, which is capable ofoperating a single channel in 64QAM, supporting two channels upstream atthe existing total maximum transmit power provides almost a doubling ofthe upstream data rate, without requiring any more maximum transmitpower or burdening the upstream system (e.g., lasers, etc.) withcarrying more power.

Thus, supporting two channels from a single cable modem, both at maximumtransmit power, may not be the best use of system resources when cablemodem cost and cable modem upstream burst capacity are the priorities.Unlike “non-disadvantaged” cable modems, which benefit greatly from morebandwidth, “disadvantaged” cable modems probably should not be usingmore bandwidth (i.e., they should be operating within one channel).

Furthermore, the overall system noise floor, which supports high densitymodulations, probably should not be raised due to increased spuriousemissions, thus acting to limit increased transmit power. Additionally,improved impairment mitigation techniques reduce the pressure for highertransmit power. For example, impairment mitigation techniques (e.g.,echoes, ingress, burst noise, etc.) have reached a level where 256QAMperformance is feasible in channels with low AWGN noise floor. By usingimpairment mitigation techniques in conjunction with SCDMA reduced codesets, even disadvantaged cable modems can operate upstream better thanDOCSIS™ 2.0 cable modems currently can, mitigating the need forincreasing the transmit power for a two channel device by 3 dB.

Also, a cable modem requiring peak power for QPSK operation does notoperate near the high end goals of DOCSIS™ 3.0, so burdening cable modem104 with 12.4 MHz allocated to the associated under-achieving user maybe inefficient. This user (in terms of DOCSIS™ 3.0 capabilities) shouldbe considered as disadvantaged (as are users in DOCSIS™ 2.0 that cannotoperate using a QPSK technique in 6.4 MHz channels even at peak power),and probably should not run up the cost for all cable modems and impairthe entire upstream spectrum at the same time.

With real world impairments in addition to AWGN, the change in capacityprovided by an additional 3 dB of average transmit power may differ fromone bit per symbol, which typically occurs with AWGN and relatively highdensity modulations, maintaining an acceptable error rate. Generally,with high density, high capacity modulations, if the benefit ofadditional average transmit power is less than a given value (e.g.,approximately ⅔ bit per symbol per dB), then it may be better to spreadthe average transmit power among more channels.

In an embodiment, cable modem system 400 is capable of determining thecapacity versus average transmit power sensitivity for each channel andincreasing/decreasing the average transmit power among the plurality ofphysical upstream channels accordingly. For example, monitoring module112 may monitor the capacity and the average transmit power to determinethe sensitivity for each channel. In this example, upstream burstmodulator 765 and/or power amplifier 775 may increase/decrease theaverage transmit power among the plurality of physical upstreamchannels.

3.0 Other Embodiments

FIGS. 1-13 are conceptual illustrations allowing an easy explanation oftransmitting information among a plurality of physical upstreamchannels. It should be understood that embodiments of the presentinvention could be implemented in hardware, firmware, software, or acombination thereof. In such an embodiment, the various components andsteps would be implemented in hardware, firmware, and/or software toperform the functions of the present invention. That is, the same pieceof hardware, firmware, or module of software could perform one or moreof the illustrated blocks (i.e., components or steps).

In this document, the terms “computer program medium” and “computerusable medium” are used to generally refer to media such as a removablestorage unit, a hard disk installed in hard disk drive, and signals(i.e., electronic, electromagnetic, optical, or other types of signalscapable of being received by a communications interface). These computerprogram products are means for providing software to a computer system.The invention, in an embodiment, is directed to such computer programproducts.

In an embodiment where aspects of the present invention are implementedusing software, the software may be stored in a computer program productand loaded into computer system using a removable storage drive, harddrive, or communications interface. The control logic (software), whenexecuted by a processor, causes the processor to perform the functionsof the invention as described herein.

In another embodiment, aspects of the present invention are implementedprimarily in hardware using, for example, hardware components such asapplication specific integrated circuits (ASICs). Implementation of thehardware state machine so as to perform the functions described hereinwill be apparent to one skilled in the relevant art(s).

In yet another embodiment, the invention is implemented using acombination of both hardware and software.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample, and not limitation. It will be apparent to one skilled in therelevant art(s) that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.Moreover, it should be understood that the method, system, and computerprogram product of the present invention could be implemented in anymulti-nodal communication environment governed by centralized nodes. Thenodes include, but are not limited to, cable modems, set-top boxes, andheadends, as well as communication gateways, switches, routers, Internetaccess facilities, servers, personal computers, enhanced telephones,personal digital assistants (PDA), televisions, or the like. Thus, thepresent invention should not be limited by any of the above-describedexemplary embodiments, but should be defined only in accordance with thefollowing claims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: at least onecommunication interface to support communication with at least oneadditional apparatus via at least one of a plurality of communicationchannels; and wherein: firstly, the at least one communication interfaceto transmit a first portion of data via a first plurality ofcommunication channels; and secondly, the at least one communicationinterface to transmit a second portion of data via a second plurality ofcommunication channels that includes a different number of channels thanthe first plurality of communication channels and such that a number ofbits per symbol within at least one of the first plurality ofcommunication channels different than when the at least onecommunication interface firstly to transmit the first portion of datavia the first plurality of communication channels.
 2. The apparatus ofclaim 1, wherein: the second plurality of communication channelsincludes at least one more channel than the first plurality ofcommunication channels; the second portion of data includes a commonamount of data as the first portion of data; and the at least onecommunication interface to transmit the second portion of data usingless power than the at least one communication interface to transmit thefirst portion of data.
 3. The apparatus of claim 1, wherein: the secondplurality of communication channels includes at least one more channelthan the first plurality of communication channels; the second portionof data includes more data as the first portion of data; and the atleast one communication interface to transmit the second portion of datausing a common amount of power as the at least one communicationinterface to transmit the first portion of data.
 4. The apparatus ofclaim 1, wherein: the second plurality of communication channelsincludes at least one more channel than the first plurality ofcommunication channels; the second portion of data includes more data asthe first portion of data; and the at least one communication interfaceto transmit the second portion of data using less power than the atleast one communication interface to transmit the first portion of data.5. The apparatus of claim 1, wherein: at least one of the secondplurality of communication channels to support a different number ofbits per symbol than at least one of the first plurality ofcommunication channels.
 6. The apparatus of claim 1, wherein: theapparatus is a communication device operative within a cablecommunication system that includes at least one of a cable modem, acable modem termination system (CMTS), and a cable headend.
 7. Anapparatus, comprising: at least one communication interface to supportcommunication with at least one additional apparatus via at least one ofa plurality of communication channels; and wherein: firstly, the atleast one communication interface to transmit a first portion of datavia a first at least one of the plurality of communication channels; andsecondly, the at least one communication interface to transmit a secondportion of data via a second at least one of the plurality ofcommunication channels that includes a different number of channels thanthe first at least one of the plurality of communication channels. 8.The apparatus of claim 7, wherein: the second at least one of theplurality of communication channels includes at least one more channelthan the first at least one of the plurality of communication channels;the second portion of data includes a common amount of data as the firstportion of data; and the at least one communication interface totransmit the second portion of data using less power than the at leastone communication interface to transmit the first portion of data. 9.The apparatus of claim 7, wherein: the second at least one of theplurality of communication channels includes at least one more channelthan the first at least one of the plurality of communication channels;the second portion of data includes more data as the first portion ofdata; and the at least one communication interface to transmit thesecond portion of data using a common amount of power as the at leastone communication interface to transmit the first portion of data. 10.The apparatus of claim 7, wherein: the second at least one of theplurality of communication channels includes at least one more channelthan the first at least one of the plurality of communication channels;the second portion of data includes more data as the first portion ofdata; and the at least one communication interface to transmit thesecond portion of data using less power than the at least onecommunication interface to transmit the first portion of data.
 11. Theapparatus of claim 7, wherein: in accordance with the at least onecommunication interface transmitting the second portion of data via thesecond at least one of the plurality of communication channels, theapparatus to lower a number of bits per symbol within the first at leastone of the plurality of communication channel.
 12. The apparatus ofclaim 7, wherein: the second at least one of the plurality ofcommunication channels to support a different number of bits per symbolthan the first at least one of the plurality of communication channels.13. The apparatus of claim 7, wherein: thirdly, the at least onecommunication interface to transmit a third portion of data via a thirdat least one of the plurality of communication channels that includes adifferent number of channels than the second at least one of theplurality of communication channels and such that the third at least oneof the plurality of communication channels to support a different numberof bits per symbol than the second at least one of the plurality ofcommunication channels.
 14. The apparatus of claim 7, wherein: theapparatus is a communication device operative within a cablecommunication system that includes at least one of a cable modem, acable modem termination system (CMTS), and a cable headend.
 15. A methodfor operating a communication device, the method comprising: operatingat least one communication interface to support communication with atleast one additional apparatus via at least one of a plurality ofcommunication channels; firstly, via the at least one communicationinterface, transmitting a first portion of data via a first at least oneof the plurality of communication channels; and secondly, via the atleast one communication interface, transmitting a second portion of datavia a second at least one of the plurality of communication channelsthat includes a different number of channels than the first at least oneof the plurality of communication channels.
 16. The method of claim 15,wherein: the second at least one of the plurality of communicationchannels includes at least one more channel than the first at least oneof the plurality of communication channels; and the second portion ofdata includes a common amount of data as the first portion of data; andfurther comprising: via the at least one communication interface,transmitting the second portion of data using less power than the atleast one communication interface to transmit the first portion of data.17. The method of claim 15, wherein: the second at least one of theplurality of communication channels includes at least one more channelthan the first at least one of the plurality of communication channels;and the second portion of data includes more data as the first portionof data; and further comprising: via the at least one communicationinterface, transmitting the second portion of data using a common amountof power as the at least one communication interface to transmit thefirst portion of data.
 18. The method of claim 15, wherein: the secondat least one of the plurality of communication channels includes atleast one more channel than the first at least one of the plurality ofcommunication channels; and the second portion of data includes moredata as the first portion of data; and further comprising: via the atleast one communication interface, transmitting the second portion ofdata using less power than the at least one communication interface totransmit the first portion of data.
 19. The method of claim 15, furthercomprising: operating the second at least one of the plurality ofcommunication channels to support a different number of bits per symbolthan the first at least one of the plurality of communication channels.20. The method of claim 15, wherein: the communication device isoperative within a cable communication system that includes at least oneof a cable modem, a cable modem termination system (CMTS), and a cableheadend.